Deep learning is the new electricity, which has dramatically reshaped people's everyday life. In this thesis, we focus on two emerging applications of deep learning - fashion and forensics.

The ubiquity of online fashion shopping demands effective search and recommendation services for customers. To this end, we first propose an automatic spatially-aware concept discovery approach using weakly labeled image-text data from shopping websites. We first fine-tune GoogleNet by jointly modeling clothing images and their corresponding descriptions in a visual-semantic embedding space. Then, for each attribute (word), we generate its spatially-aware representation by combining its semantic word vector representation with its spatial representation derived from the convolutional maps of the fine-tuned network. The resulting spatially-aware representations are further used to cluster attributes into multiple groups to form spatially-aware concepts (e.g., the neckline concept might consist of attributes like v-neck, round-neck}, \textit{etc}). Finally, we decompose the visual-semantic embedding space into multiple concept-specific subspaces, which facilitates structured browsing and attribute-feedback product retrieval by exploiting multimodal linguistic regularities. We conducted extensive experiments on our newly collected Fashion200K dataset, and results on clustering quality evaluation and attribute-feedback product retrieval task demonstrate the effectiveness of our automatically discovered spatially-aware concepts.

For fashion recommendation tasks, we study two types of fashion recommendation: (i) suggesting an item that matches existing components in a set to form a stylish outfit (a collection of fashion items), and (ii) generating an outfit with multimodal (images/text) specifications from a user. To this end, we propose to jointly learn a visual-semantic embedding and the compatibility relationships among fashion items in an end-to-end fashion. More specifically, we consider a fashion outfit to be a sequence (usually from top to bottom and then accessories) and each item in the outfit as a time step. Given the fashion items in an outfit, we train a bidirectional LSTM (Bi-LSTM) model to sequentially predict the next item conditioned on previous ones to learn their compatibility relationships. Further, we learn a visual-semantic space by regressing image features to their semantic representations aiming to inject attribute and category information as a regularization for training the LSTM. The trained network can not only perform the aforementioned recommendations effectively but also predict the compatibility of a given outfit. We conduct extensive experiments on our newly collected Polyvore dataset, and the results provide strong qualitative and quantitative evidence that our framework outperforms alternative methods.

In addition to searching and recommendation, customers also would like to virtually try-on fashion items. We present an image-based VIirtual Try-On Network (VITON) without using 3D information in any form, which seamlessly transfers a desired clothing item onto the corresponding region of a person using a coarse-to-fine strategy. Conditioned upon a new clothing-agnostic yet descriptive person representation, our framework first generates a coarse synthesized image with the target clothing item overlaid on that same person in the same pose. We further enhance the initial blurry clothing area with a refinement network. The network is trained to learn how much detail to utilize from the target clothing item, and where to apply to the person in order to synthesize a photo-realistic image in which the target item deforms naturally with clear visual patterns. Experiments on our newly collected dataset demonstrate its promise in the image-based virtual try-on task over state-of-the-art generative models.

Interestingly, VITON can be modified to swap faces instead of swapping clothing items. Conditioned on the landmarks of a face, generative adversarial networks can synthesize a target identity on to the original face keeping the original facial expression. We achieve this by introducing an identity preserving loss together with a perceptually-aware discriminator. The identity preserving loss tries to keep the synthesized face presents the same identity as the target, while the perceptually-aware discriminator ensures the generated face looks realistic. It is worth noticing that these face-swap techniques can be easily used to manipulated people's faces, and might cause serious social and political consequences.

Researchers have developed powerful tools to detect these manipulations. In this dissertation, we utilize convolutional neural networks to boost the detection accuracy of tampered face or person in images. Firstly, a two-stream network is proposed to determine if a face has been tampered with. We train a GoogLeNet to detect tampering artifacts in a face classification stream, and train a patch based triplet network to leverage features capturing local noise residuals and camera characteristics as a second stream. In addition, we use two different online face swapping applications to create a new dataset that consists of 2010 tampered images, each of which contains a tampered face. We evaluate the proposed two-stream network on our newly collected dataset. Experimental results demonstrate the effectiveness of our method.

Further, spliced people are also very common in image manipulation. We describe a tampering detection system containing multiple modules, which model different aspects of tampering traces. The system first detects faces in an image. Then, for each detected face, it enlarges the bounding box to include a portrait image of that person. Three models are fused to detect if this person (portrait) is tampered or not: (i) PortraintNet: A binary classifier fine-tuned on ImageNet pre-trained GoogLeNet. (ii) SegNet: A U-Net predicts tampered masks and boundaries, followed by a LeNet to classify if the predicted masks and boundaries indicating the image has been tampered with or not. (iii) EdgeNet: A U-Net predicts the edge mask of each portrait, and the extracted portrait edges are fed into a GoogLeNet for tampering classification. Experiments show that these three models are complementary and can be fused to effectively detect a spliced portrait image.